The present invention relates to the high speed printing industry, and more particularly a system and method for flowing variable data into a page description language file in a high speed printing environment.
Application programs, such as word processors, illustrators, and computer-aided design systems are software packages used to create a document (text and graphics) on a computer screen and to simultaneously generate a page description language (xe2x80x9cPDLxe2x80x9d) specification, which is to be transferred to the printer or to any other type of raster or output device for creating a hard copy or copies of the document. Alternatively, a PDL specification can be generated by a programmer without the assistance of an application program.
The printer executes the PDL specification to generate a bitmap of the document, or a raster-data representation of a document, and eventually transfers the bitmap or raster-data to the physical medium. A typical PDL language, such as PostScript (a registered trademark of Adobe Corporation) defines a page of the document as containing a number of data areas, where each data area contains either graphic or alpha-numeric data. Each data area is defined by a xe2x80x9cgraphic state,xe2x80x9d which is a collection of parameters for controlling the representation and appearance of text and graphics. For example, the graphic state can include a set of text attributes such as scale-factor, type-font, etc. In PostScript, an example of a PDL command used to build a graphic state can be: xe2x80x9ctwenty rotate,xe2x80x9d and xe2x80x9c/Times-Roman find font 14 scalefont setfont.xe2x80x9d Examples of PDL commands used to define the graphic or alpha-numeric data that is displayed in the data area include: 00 moveto and (ABC) show. The entire group of PDL commands used to define a document is hereinafter referred to as the xe2x80x9cPDL specification.xe2x80x9d
In variable data printing each printed document shares a common template and there is at least one area in the template that changes for each printing of the template. Typical PDL languages are not designed for high-speed variable data printing because, with PDL languages and PDL interpreters, even if a single item of data in the document changes, an entirely new PDL specification must be created and interpreted. For example, if one-hundred thousand copies of a mass-mailing advertisement were to printed (i.e., each copy of which is identical except for the mailing address), it is typically necessary to generate a new PDL specification for each copy to printed. Hence, to generate one-hundred thousand advertisements, it would be necessary to generate one-hundred thousand PDL specifications, even though each advertisement is virtually the same except for the variable data area. The processing time required to interpret and render one-hundred thousand PDL specifications is enormous, significantly slowing the entire printing system.
Furthermore, typical PDL languages do not include any text or data flowing capabilities. These features are usually implemented by the application program, and when such an application program flows data (such as text) into a PDL document, the calculations to determine where to place the data are completed prior to the generation to the PDL specification. Accordingly, variable data cannot be flowed into a template document without creating a new PDL specification for each document. Accordingly, there is a need for a high-speed printing operation having the ability to merge variable data into a template defined by a PDL specification; and in particular, having the ability to flow variable data into a template path defined by PDL specification in a high-speed printing operation.
It is an object of the present invention to provide a system and method for flowing variable data (such as text data, image data, bar code data and the like) into a path of a template defined by a PDL specification in a high-speed printing operation. It is a further object of the present invention to provide the ability to generate a plurality of merged bitmaps, which are each essentially a copy of a template, except for at least one portion of the template that contains an arbitrary path. In that path, each merged bitmap can contain a different set of variable data merged into it. The template is defined by a page description language, and the page description language only needs to be processed or interpreted once before creating all of the merged bitmaps, thus providing an extremely high-speed variable data printing operation.
The computer implemented method for flowing data into an arbitrary path defined by a page description language specification (xe2x80x9cPDL specificationxe2x80x9d) generally comprises the steps of: processing (interpreting) the PDL specification to produce a template; designating a path defined in the PDL specification as a wrapping path; associating a block of variable data with the wrapping path; and merging variable data, according to the path boundary and according to a predefined flow rule, into a copy of the template.
The method of the present invention is accomplished by executing a control task in conjunction with a PDL interpreter program. The control task generates a template display list based upon the PIDL commands in the PDL specification. The display list includes a plurality of rendering commands, where each rendering command designates a particular data area or object to be rendered, the graphics state to be applied to the data area and the offset address at which the rendered object, if any, in the data area is to be overwritten onto the final bit map. The graphic states for each data area are set forth in the PDL specification, and pertain to the print attributes that describe how particular graphic or alpha-numeric data is to appear on the printed page. These attributes can include the size, font, position, orientation, location, and the like.
The control task, during the PDL interpretation procedure, monitors the data areas defined by the PDL specification to watch for variable data paths defined by the PDL code. If the control task identifies a path as being a variable data path, it reserves the graphic-states associated with that variable data path in a cache or memory, and then moves on to the next data area defined in the PDL specification, preferably without allowing the path data to be added to the template display list.
Once the interpreter program completes its interpretation of the PDL specification, the control task saves the template display list in memory without dispatching a bitmap of the template to the printer. Subsequently, a merge task is initiated which accesses a variable data record from a merge file; associates the variable data record to a particular variable data path; creates representations of the variable data, such as rendering commands according to the reserved graphic states pertaining to that particular variable data path, according to the boundary of the particular variable data path and according to a predefined flow rule; and then generates a merged bitmap by processing the template display list and the variable data rendering commands. The final merged bitmap that may then be dispatched to the printer. This merge task is repeated for each variable data record in the merge file associated with that particular variable data path to create a plurality of the merged bitmaps.
Thus, the PDL specification of the template need only be interpreted once, saving significant processing time for the variable printing operation, because the reserved graphic states may be utilized over and over again to create the flowed data bitmap for each variable data record contained in the merge file.
How the control task identifies a particular PDL path defined in the PDL specification as being unique, i.e., as being identified as a wrapping path, is an important step in the above process. This is accomplished by providing a text command in the PDL specification that defines one or more characters that are recognized by the control task as being special characters, as opposed to merely being characters that are to be included on the printed page. The control task monitors all text strings defined by the PDL specification for such special characters, and responsive to a detection of the special character in the text string defined by the text command, the control task identifies the path command that has a predetermined relationship with the text command in the PDL specification. This predetermined relationship can be satisfied by the first path command to follow the text command in the PDL specification or by the path command that is xe2x80x9cgroupedxe2x80x9d with the text command in the PDL specification.
In the preferred embodiment of the present invention, the characters xe2x80x9c less than  less than xe2x80x9d and xe2x80x9c greater than  greater than xe2x80x9d are used as part of a special text string to define an area as a variable data area. And if that special text string also includes the string wrap then the control task will recognize that the very next path command appearing in the PDL specification will be a unique path, in this case a path for flowing variable text bitmaps into.